Rabbitte will urge Labor delegates to support the strategy, aimed at removing the current Fianna Fail/Progressive Democrats coalition at the next Dail elections.
The elections are expected either next year or 2007.
While Rabbitte is widely tipped to be successful, it should not all be smooth sailing.
His plans came under attack on Tuesday from union bosses who warned that Fine Gael had tricked Labor into considering the pact in a bid to save it from political irrelevance.
ATGWU regional secretary Michael O’Reilly warned that Fine Gael was only interested in improving its own support.
“Fine Gael is cynically using Labor to increase its own support by offering a pre-election pact,” he said. “Their proposed pre-election pact is not a political strategy. It is an attempt to use Labor to maximize transfers to win more seats, even if they can’t increase their popular support.
“The only reason that Fine Gael is trying to lure Labor into a pre-election pact is to enhance its status as the main opposition party and to halt any Labor improvement. Without such a pact, they could lose even further ground.
“Rather than cozying up to an increasingly irrelevant Fine Gael, it should present itself as the real alternative to Fianna Fail and build alliances with other progressive parties and independents to achieve that aim,” he said.
Around 1,100 delegates will vote on the proposal in Tralee on Saturday morning. The conference will be screened live on RTE television.
The national executive’s motion, which would enable Rabbitte to take whatever steps he deemed necessary to “see the government parties removed from office”, is countered by a motion calling for a “Labor-first” policy”. The counter-motion proposes that the party signs up to no such pre-electoral pacts.
It is supported by several senior Labor party members, including vice-chairman Henry Haughton, Dublin North East TD Tommy Broughan and former deputy leader Brendan Howlin.
The Green Party ruled itself out of any such coalition plans last week at its own conference. The vote has been welcomed by many within Fine Gael who believe that it will be much easier to manage an election campaign with two parties instead of three.
Fianna Fail and the PD’s have recently attacked Green policies as unworkable and both Labor and Fine Gael members feared that a coalition including the party could be much more easily be left open to attack from the government parties.